Front to back airflow is a NEBS (Network Equipment Building Systems) requirement for equipment installed in a central office. Straight (rather than curved) airflow gives optimum thermal performance. Consequently, the most optimum cooling solution is to have fans mounted to the rear of the equipment, e.g., router chassis. Although techniques such as rail-guided fan tray assemblies are sometimes used to improve airflow in equipment, various shortcomings and deficiencies continue to persist.